The present invention is concerned with a blood lancet device for taking blood for diagnostic purposes, this device having a housing with an exit opening for the lancet, a lancet guide for guiding the puncturing and return movement of the lancet, a spring drive for movement of the lancet and a stop by means of which the lancet is kept in a position remote from the part of the body from which blood is to be taken.
In order to obtain small amounts of blood for diagnostic purposes, lancets are used which a laboratory assistant briefly sticks into a patient's finger tip or into some other suitable part of the patient's body. A disadvantage of this is that the patient can see what is happening and the nature of the resulting wound depends upon the user of the lancet and cannot, therefore, be reproduced. Furthermore, it is quite common that a second person must carry out the puncturing operation since the degree of protection against self-injury is very great.
Blood lancet devices are also known, with the help of which a patient can sample his own blood. However, here again, the puncturing operation is generally visible. Furthermore, in the case of these devices, there is a possibility that a lancet intended for single use is employed several times successively by operating the cocking lever of the device. This results in a considerable danger of infection.
One example of such a known device is described in German Patent Specification No. 459,483. In this case, the lancet is driven for the puncturing movement by means of a spiral spring which can be tensioned by operating a pull rod connected to the lancet. In the tensioned state, a stop connected with the lancet engages in a recess provided laterally in the collar-shaped housing of the lancet device. A patient who wishes to use this known device for sampling his own blood must overcome a considerable feeling of inhibition in order to activate the lateral release knob without simultaneously automatically pulling away the finger tip or other part of the body from which the blood is to be taken. A further disadvantage of this known device is that the driving spring can oscillate, which can result in a jagged puncturing and, consequently, in wounds which heal with difficulty.